La Niña brings cooler than normal and wetter than normal winter weather for the Pacific Northwest...usually.
Cold storms with high amounts of rain and mountain snow, along with a few more rounds of lowland snow, keep the precipitation above average and temperatures below.
Cooler and wetter than the average for the Pacific Northwest, La Niña also creates drier than average winters over the southwest United States; most often, a drought builds.
Not this year! Our rare, third-consecutive La Niña winter has been filled with variability.
La Niña’s large fluctuations in the Jetstream, which acts as the steering current for storms, carried numerous winter storms southward into California, dousing drought levels to non-existence and deepening the mountain snowpack of the Southwest.
This winter, a moderate La Niña is intact with the equatorial Pacific’s cooler sea surface. Now, a slow gradual transition is developing.
Over the next few months, there should be just enough warming of water and shifts in the tradewinds to transition March through May into an ENSO-Neutral phase.
The chance of having a Neutral phase in place by June is 82%.
Neutral does not bring a non-eventful winter season. If we get a few strong storms, they could bring trouble.
Some of our largest and most damaging windstorms, heavy snow, and atmospheric Rivers happened in neutral years.
Remember the Hanukkah Eve Windstorm of December 2006? That was a neutral year.
On Dec. 14 and 15, over 1 million people lost power, including Sea-Tac International Airport, which canceled all flights. Seattle School District closed along with numerous surrounding districts, and the Seattle P.I. was unable to publish newspapers due to the power outage. Flooding was a huge part of the storm as a series of atmospheric rivers brought record rainfall over the first part of the month, and there were a significant number of deaths due to falling trees and carbon monoxide poisoning.
What seemed to be an endless round of snow in January 2020, that too, was a winter in the neutral phase. The most recent ENSO Neutral years were
- 2019-2020
- 2016-2017
- 2013-2014
- 2012-2013
But we are not out of the La Nina influence yet! Cold temperatures, wind and snow are just around the corner for the last week of January.